Diphosphates of divalent aryl hydrocarbons



United States Patent 5 Claims. (Cl. 260930) ABSTRACT OF THE DISCLOSURECompounds are provided for reducing rumble and preignition of fuels usedfor operation of internal combustion engines, having the followingformula wherein R is a divalent aliphatic hydrocarbon group of one totwelve carbon atoms, Ar is alkyl-substituted phenyl and R is a memberfrom the group consisting of phenyl, alkyl-substituted phenyl andchloro-substituted phenyl.

The present invention relates to novel lead-containing fuels foroperation of internal combustion engines and to the operation of suchengines with such fuels, and is a division of our application Serial No.213,578, filed July 31, 1962 now US. Patent 3,254,973; issued June 7,1966. More particularly, the present invention relates to novellead-containing fuels that reduce the abnormal combustion phenomenaknown as rumble and minimize preignition in operation of internalcombustion engines.

As is well known to those skilled in the art, the compression ratio ofinternal combustion engines has been steadily increased. Suchcompression ratio increases have led to increased incidence of acombustion phenomenon known as rumble which is more prevalent in engineshaving compression ratios of at least :1 and higher. It is postulatedthat rumble is caused by abnormally high rates of pressure riseresulting from too rapid burning of the fuel-air mixture wherebyvibrations are produced in overstressed engine parts causing a lowfrequency thudding noise that is associated with rumble.

As is also well known to those skilled in the art, the addition of leadantiknock agents, such as tetraethyl lead and tetramethyl lead ormixtures thereof, to increase octane ratings, is a well-establishedpractice. It is also well known that the use of leaded gasolines havedisadvantages, notably the occurrence of preignition. As the termimplies, preignition is the ignition of the air-fuel mixture in thecylinder before the regular, timed spark ignition whereby the enginewill behave as if the spark has been advanced beyond its normal timing.Such a phenomenon is, of course, a barrier to further increase incompression ratios. Thus, the problem of preignition has become moreacute because of the trend to engines of increased compression ratio.

As is contemplated herein, preignition is caused by incandescentparticles of combustion chamber deposits. Such deposits consist of amixture of carbonaceous material and lead salts formed by decompositionof the lead antiknock compounds. The lead salts resulting from thecombustion of a leaded motor fuel are complex in nature. It is believedthat they include lead chloride or bromide, lead oxide and lead sulfate,as well as mixed salts thereof formed through solid-solid reactions.These lead compounds have a catalytic effect upon the oxidation of the3,360,591 Patented Dec. 26, 1967 carbon in the combustion chamberdeposits. The rapid oxidation of the carbon particles causes them toglow and to remain aglow for considerable periods of time after thecombustion cycle. Accordingly, these glowing particles are presentduring the subsequent combustion cycle and cause preignition. Althoughpure carbon must be heated to about 1400 F. to make it glow, in thepresence of lead salts the carbon glow is initiated as much as about 700F. lower. Thus, it will be appreciated that obviating or minimizing thecatalytic oxidation effect of the lead salts will reduce preignition.

Certain phosphorus compounds are known to those skilled in the art to beeffective types of compounds for rendering inert the stated catalyticeifect of lead salts and, in general, it is known that a largerconcentration of the phosphorus compounds is required in the fuel tominimize the rumble problem than is required to control the other formsof surface ignition. For example, in the use of a phosphorus compoundsuch as tricresyl phosphate, 0.2 theory is normally required for thecontrol of Wild ping type of surface ignition whereas 0.4 to 1.0 theoryis normally required to control rumble. In connection with theproportional amount of phosphorus compound to the lead compound, as usedherein, theory is the quantity of additive required to furnish 2 atomsof phosphorus for 3 atoms of lead in the fuel to form Pb (PO It has nowbeen found that rumble and deposit-induced preignition of spark-ignitioninternal combustion engines can be materially reduced by'addition ofcertain phosphorus-containing compounds and combinations thereof inleaded motor fuels and, more particularly, that, by use of thephosphorus-containing compounds embodied herein, a marked and unexpectedincreased activity on a phosphorus basis is obtained as compared tocertain conventional phosphorus-containing additives for such purposesin leaded motor fuels.

The fuels contemplated herein are mixtures of hydrocarbons suitable foruse in internal combustion engines of the spark ignition type, includingmotor gasolines and aviation gasolines. In general, motor gasolines havean initial boiling point as low as about 80 F. and an end boiling pointas high as about 440 F. and boil substantially continuously between theinitial boiling point and the end boiling point. Aviation gasolines, onthe other hand, are mixtures of hydrocarbons having an initial boilingpoint of about 80 F. and an end boiling point of about 340 F. andboiling substantially continuously between these points. Motorgasolines, at present, can, for example, contain up to about 4.0 ml. oftetraethyl lead per gallon whereas aviation gasolines can contain up toabout 4.6 mL/gallon of such a material. In general, the

. antiknock compound is an organic lead compound, as, for

example, lead tetraalkyls, such as lead tetraethyl, lead tetramethyl,and mixtures thereof, and which gasolines are commonly referred to asleaded gasolines. Furthermore, it is common practice to add to theleaded gasoline a halohydrocarbon scavenger and, typical thereof aresubstances such as ethylene dichloride, ethylene dibromide, acetylenetetrabromide, and mixtures thereof. It is also common practice to use acombination of ethylene dichloride and ethylene dibromide in leadedmotor gasolines whereas ethylene dibromide alone is used in leadedaviation gasolines. The amounts of scavenger utilized are calculated toavoid excessive wear and corrosion of the operating parts of the enginesuch as exhaust valves, and achieve effective scavenging of leaddeposits. Thus, in the case of leaded motor gasolines, it has been thepractice to use one theory of ethylene dichloride and 0.5 theory ofethylene dibromide. On the other hand, it has been the practice to useone theory of ethylene dibromide in leaded aviation gasoline. As usedherein, the term ther r 3 ory, as applied to the proportional amount ofscavenger Ar is an aryl or alkaryl group such as may be derived to lead,is intended to mean the amount of the scavenger from phenol andsubstituted phenols as, for example, required to convert all the leadpresent into a lead salt as, from cresol, xylenol, isopropyl phenol,t-butyl phenol, for example, into a lead salt such as lead chloride ornonyl phenol, halogen-substituted phenols such as chlorobromide.phenols, polychlorophenols, etc.', and R is alkyl, aryl or Thephosphorus-containing compounds embodied for alkaryl, and,illustratively, methyl, isopropyl, octyl, tolyl, use in practice of thisinvention are high molecular weight xylyl, t-butyl phenyl, nonyl phenyl,etc. Preferably, R is phosphates having the structural formula: anaromatic group as, generally, the presence of an aro- I matichydrocarbon group in the R positions provides 0 A R A O compounds thatare less antagonistic to the lead-containr P ing anti-detonant additivesused in gasolines. As a very 0 specific embodiment, the presentinvention is carried out wherein R is a divalent aliphatic hydrocarbongroup, with a compound of the following formula:

CH3 CH I $1323 1 \O CH: O 2 4,4 isopropylldene diphenol bis (di-o-tolyl)phosphate straight or branch chain, Ar is a member from the group Stillother compounds embodied for use in practice of consisting of aryl andsubstituted-aryl in which the subthis invention are the following:

CH CH I ?H;

I II a Q (5H: 0 g

C H3 4,4-sec-butylldene dlphenol bis (dt-o'tolyphosphate) 11H 0 t-Q-r-Q- I I C0 1 9 2 4,4-isopropy1ldene diphenol bis (di-p-nonylphenolphosphate) (111; O H; C H3 C Ha I (EH: I I

I II 3 0 CH3 0 l 4,4-isopropylidene bis (2-methylphenol) bis (di o-tolylphosphate) 4,4'-isopropy1idene bis (tetrachlorophenol)bis-(di-o-chlorophenyl phosphate) stituent is preferably an alkyl groupor a halogen (e.g.,

CH chlorine), and R is the same or different members from a the groupconsisting of alkyl, aryl, alkaryl and halogen- ICHaOI1P*O OI|[0CH ]1substituted aryl. Preferably, in such high molecular weight 011 (Iphosphates, R is a lower molecular weight aliphatic hy- 4,4-15opropy1idediphenolbis (dimethyl phosphate) drocarbon group containing, forexample, from one to about: 12 carbon atoms as in the followingillustrative groups; methylene, ethylidene, propylidene, anddodecylideneand still more preferably, divaent groups such I oflrqjm as:

( J HJLEC 4,4'-isopropylidene bis (2-t-buty1pheno1) bis (dimethylphosphate) CH3 CH3 2 (dimethoxyphosphinyloxyphenyl) -2 (di(o-methylphenoxy) phosphinyloxy phenyl) propane In reference tocompounds of the foregoing formula wherein Ar and R are aryl orsubstituted-aryl groups, they may be synthesized by heating anappropriate phenolic compound with phosphorus oxychloride at, forexample, 80 to 300 C. depending on the particular catalyst employed. Forsuch a process, metal halides, as MgCl and A101 are particularlysuitable catalysts as they permit condensation times of 6-9 hours at 200C. Evolution of hydrogen chloride generally starts at about 100 C. andis completed at about 225 C. when anhydrous MgCl is used as thecatalyst. If desired, the reaction may be carried out in steps withisolation of the intermediates. Thus, and preferably using an excess ofthe phenolic reactant to drive the reaction to completion, the pluralstep process can be carried out as follows:

M Clz amines or vacuum 0 The alkyl phosphoryl halide may be prepared bythe addition of an alcohol to phosphorus oxychloride in approximatelystoichiometric amounts at 020 C. with removal of the evolvedhydrochloric acid by application of reduced pressures or byneutralization with amines such as pyridine, ammonia, etc. Purificationmay be achieved by washing till neutral and fractional distillation. Asecond method of preparing the phosphoryl halide is by the addition ofchloride to a dialkyl hydrogen phosphite.

The alkyl phosphoryl halide may then be esterified with a phenoliccompound by the Schotten-Baumann technique. The phosphoryl halide isadded to a solution or suspension of the sodium arylate at 1030 C. Theester product is separated and washed with dilute aqueous sodiumhydroxide solution and water till neutral. Further purification, asdesired, may be achieved by steaming to remove traces of alcohol,decolorization with permanganate solution and/or adsorbents, filtrationand dehydration.

In a specific embodiment, the following procedure was used forpreparation of 4,4-isopropylidene diphenol bis (di-o-tolyl phosphate)(a) Preparation of di-o-tolyl phosphorochloridate. Phosphorusoxychloride (6 m., 920 g.) plus anhydrous magnesium chloride (9 g.) wereadded to a 5 liter flask equipped with a thermometer, a refluxcondenser, a stirrer and an addition funnel. The reflux condenser wasconnected to two gas wash bottles in series containing known amounts ofaqueous sodium hydroxide and phenolphthalein indicator (to measure theevolved hydrogen chloride). O-cresol (12 m., 1324 g., 98% pure) wasadded in portions to the flask with stirring and heating. Three hundredgrams of the o-cresol were added initially; the remainder during 255minutes as the reaction mixture was heated to 110 C. (Hydrogen chloridebegan to evolve at about C.). Heating and stirring were continued for anadditional two hours during which the temperature rose to 190 C.Nitrogen gas was passed through the reaction mixture during the last 55minutes of this period to help expel the evolved HCl. A total of 12moles of HCl were evolved during the reaction and were measured byabsorption in the standardized aqueous sodium hydroxide solutions.

The reaction mixture was distilled under vacuum through a packed column.

Di-o-tolyl phosphorochloridate cuts distilling at 182 187 C. at 5.0 to5.5 mm. pressure were combined. Weight of this combined material was 824g. Analyses of this product showed 12.1% C1 and 10.5% P; theoreticalanalyses of di-o-tolyl phosphorochloridate are 12.0% C1 and 10.4% P.

(b) Preparation 0 the 4,4'-is0pr0pylidene diphenol bis (di-o-tolylphosphate).-The di-o-tolyl phosphorochloridate (1 m., 296.7 g.) and bisphenol A (4,4'-isopropyli dene diphenol) (0.5 m., 114.1 g.) were placedin a fournecked flask equipped with a stirrer, thermometer, refluxcondenser and a dropping funnel. Anhydrous magnesium chloride (0.5 g.)was added to the mixture. All gases evolved from the reaction werepassed through two wash towers containing measured amounts of aqueoussodium hydroxide solution and phenolphthalein indicator. The mixture washeated with stirring from 25 to 215 C. during minutes and thenmaintained at 215 C. for 25 minutes. Nitrogen was passed through themixture at 215 C. to help expel the evolved HCl. Evolution of HClstarted at about 85 C. A total of about 0.9 m. of HCl was evolved.

Four hundred cc. of benzene was added to the reaction product. It wasthen washed with 50 cc. of 5% aqueous hydrochloric acid; 100 cc. of 5%aqueous sodium hydroxide; 50 cc. of 0.25% aq. HCl; and finally withwater until neutral. Centrifuging or adding minor amounts of petroleumether (less than 50 cc.) were used to break the emulsions which tendedto form during the washings. The solvents were then stripped from thereaction product under vacuum until a pot temperature of 210 C. at apressure of 19 mm. Hg was attained. Weight of product was 367 g.

To further purify this material, 355 g. of the above product wasdissolved in 500 cc. benzene and passed through 500 g. of Alcoaactivated alumina F-20 packed in a 25" x 1%" column. The benzene solventwas stripped from the eluate until a pot temperature of 205 C. at 10 mm.Hg was reached. The following analyses were obtained for the purifiedester.

The 'amount of phosphorus-containing compounds used in the presentinvention is dependent on the lead content. Accordingly, instead ofdefining the amount in terms of weight or volume concentrations, it ismore accurate to expresse the amount of phosphorus-containing compoundare modified to give a compression ratio of 11:1. Standard carburationand ignition systems are employed. The engine is equipped with aconventional Dynaflow transmission connected to a TLC-74 D.C.dynamometer (200 H.-P.). The dynamometer contains a flywheel whichproduces inertia characteristics like those imposed by the weight of atypical passenger car. In order to eliminate effects attributable tofluctuating conditions of intake air, it is supplied from an airconditioning system at constant temperature and humidity.

The engine is operated for 240 hours on an alternating operationschedule consisting of one hour at constant speed running at 1700 r.p.m.followed by one hour of cyclic operation between 500 and 1700 r.p.m. Theengine in terms of a theory. Such a theory is, as aforesaid, the 15operating conditions are set forth in Table I.

TABLE I Type of Operation: Alternating fixed and cyclic.

Type

Fixed Cyclic Duration (hrs) Action Run Idle Accel. Run Decel.

Duration (secs) 14 120 16 Engine Speed (r.p.ru.) 1. 1, 700 500 1, 700Dynarnometer Speed (r.p.m.) 1, 640 400 1, 640 B. h.p.; Dynamometer 15 0.6 15 Manifold vacuum Hg) Jacket coolanttemu, F 180 180 180 180 180 Inletair (Dry bulb F.) 105 105 105 105 105 (Wet b ulb F.) 69 9 69 69 69 Basicignition timing, BTC 5 5 5 5 5 1 To 1,650. 2 To 400; 8 min.

amount of phosphorus-containing compound stoichiometrically required toreact with all the lead present in the gasoline formulation to form leadorthophosphate. Thus, 0.5 theory would indicate one-half the amount ofphosphorus-containing compound stoichiometrically required to react withall the lead present. Generally, in practice of this invention, theamount of the phosphorus-containing compound will be between about 0.02theory and gg; rumbl Rumble g about 2.0 theory, and preferably, betweenabout 0.1 theory Mediim i 7 5 and about 0.5 theory. Li ht rumble Inaddition to additives such as lead anti-knock com- Trgace rumble 2 5pounds and scavengers such as halohydrocarbons, and No I M thephosphorus compounds embodied herein, the gasoline um e 0 compositioncan contain other additives. Thus, for example, the gasolines caninclude dyes, carburetor de-icing agents such as isopropyl alcohols andlauryl mercaptoacetic acid, corrosion inhibitors such as polymerizedfatty 'acids and salts of petroleum sulfonic acids, metal deactivatorssuch as N,Ndisalicylidene-1,2-diaminopropane, antigurn formationadditives such as 2,6-ditertiarybutyl paracresol, etc.

The following examples are for the purpose of illustrating thepreparation and the effectiveness, in the defined rumble andpreignitiontests, of the compositions of this invention. It is to beunderstood that this invention is not to be limited by the specificcompositions of the examples or to the operations and manipulationsinvolved. Other additives as described hereinbefore can be used as thoseskilled in the art will readily appreciate.

, The rumble test gine with a 322 cu. in. displacement. The pistoncrowns The average of the 15 ratings constitutes the daily rumble rate.An average of these daily rates (commencing with the 72 hour rating) isthe overall rumble rating, which is the reported value.

Preignition test This test is conducted with a Labeco 17.6 crankcaseequipped with a single cylinder O1ds modified conversion assembly whichincludes a 1953 Oldsmobile combustion chamber mounted on a wet sleevecylinder. The engine, in good mechanical condition, is prepared for testwith clean valves, combustion chamber, and new spark plug. Following aninitial one-hour Warm-up, the engine is run under preset cyclicconditions continuously for a total test time of hours. Performace ofthe test gasoline is judged by the rate of preignition counts per hour.

For the preignition test, the engine is considered ready for test if aof 5. 13 H.P. output (22 lbs.

Toledo scale) can be obtained on clear isooctane at the followingconditions:

MAP (manifold air pressure) 30" Hg abs. Air: Fuel ratio 13.0/1. Speed1400 r.p.m. Spark advance TDC. Temperature, F.:

Jacket 212.

Oil 170.

Air 100.

EXAMPLE 1 The fuel used for this example was a platinum reformate of thefollowing properties and which contained an anti-oxidant(2,6-ditertiarybutyl paracresol), a metal deactivator(N,N'-disalicylidene 1,2-diaminopropane) and a scavenger of ethylenedichloride and ethylene dibromide.

Gravity, API 42 4 RVP, lbs. 4.5 Distillation, F.:

Initial 92 143 50% 256 90% 328 End point 410 Mercaptan sulfur, p.p.m.3.0 Lamp sulfur, wt. percent 0.0004 Aromatics, vol. percent 69:2 Olefin,vol. percent 0.7 Saturates, vol. percent 30.1 Research octane No. 3 ml.TEL/gal 105.8

RUMBLE ENGINE TEST RESULTS Run No. Additive Rumble Rating 1 Base Fuel...None 8.1 2 Base Fuel 0.4 theory diphenyl tolyl phosphate 6. 3 3 BaseFuel.-. 0.4 theory 4,4-isopropylidene diphenol bis 1. 2

(di-o-tolyl phosphate).

As is apparent from the foregoing, the base fuel was markedly suppressedagainst rumble by use of an additive embodied for use'herein (Run 3) ascompared to the rel-atively small extent of suppression resulting fromuse of a conventional phosphorous-containing additive (Run 2) at thesame 0.4 theory.

EXAMPLE 2 Base gasoline composition same as Example 1.

As is apparent from the foregoing, use of the additive embodied herein(Run 3) resulted in markedly improved performance in the preignitiontest as compared to the conventional additive (Run 2) at the same theoryconcentration.

Although the present invention has been described with preferredembodiments, it is to be understood that modifications and variationsmay be resorted to, Without departing from the spirit and scope of thisinvention, as those skilled in the art 'will readily understand. Suchvariations and modifications are considered to be within the purview andscope of the appended claims.

What is claimed is:

1. A chemical compound of the following formula: RO\ OR /F0ArOArOPwherein R is a divalent aliphatic hydrocarbon group of one to twelvecanbon atoms, Ar is alkyl-substituted phenyl and R is a member from thegroup consisting of phenyl, alkyl-su bstituted phenyl andchloro-substituted phenyl.

2. A compound, as defined in claim 1, wherein R is 3. A compound, asdefined in claim 1, wherein R is alkyl-substituted phenyl.

4. A compound, as defined in claim 1, wherein R is tolyl.

5. 4,4'isopropylidene diphenol bis (di-o-to1yl phosphate).

References Cited UNITED STATES PATENTS 8/1950 Barrett 260-930 6/1953 Toy260-930 rhnii UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPatent No. 3,360,591 December 26, 1967 John J. Giammaria et a1.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 3, lines 9 to 11, for that portion of the formula reading OR OR-O\ read -III\ same column 3, lines 70 to 75, the expressions shouldappear as shown below instead of as in the patent:

T F C- and C- CH3 C H column 4, below the second formula, for"(di-o-tolyphosphate)" read (diotolylphosphate) same column 4, lines 62to 65, for that portion of the formula reading "[CH O] P-O-" read [CH O]P-O- same column 4, line 66, for "4,4-

isopropylide" read 4,4-isopropylidene column 5, line 73, for "chloride"read chlorine column 10, lines 25 to 28, for that portion of the formulareading "-ArO-Ar" read Ar-R-Ar- Signed and sealed this 25th day ofFebruary 1969.

(SEAL) Attest:

EDWARD J. BRENNER Commissioner of Patents EDWARD M.FLETCHER,JR.Attesting Officer

1. A CHEMICAL COMPOUND OF THE FOLLOWING FORMULA: